Increases the duration of your Chill effects by X secs, reduces the target's speed by an additional Y%, and reduces the target's healing received by Z%.
Permafrost is a mage talent that increases the effectiveness of the mage's chill effects, increasing the duration by 1 sec. per rank, up to 3 sec. max, reduces movement speed by an additional amount, up to 10% at max rank 3, and reduces the target's healing received up to 20% at max rank 3. The additional reduction to movement speed is an additive amount, meaning that a snare that normally slows by 50% will now slow by 60%. This talent is popular with frost mages that do a lot of kiting, either against single mobs or when doing frost AoE grinding on multiple mobs at once.
Some spells gain a particular advantage from the increased chill duration. Blizzard, with points in Improved Blizzard normally has a chill of 1.5 seconds, which is increased to 4.5 seconds with Permafrost, three times the duration. Cone of Cold normally has a chill duration of 8 seconds, which is increased to 11 seconds with Permafrost, making the duration longer than the spell's cooldown of 10 seconds.
Chill duration increase
This talent can be combined with the deep Frost talent Chilled to the Bone for a total 20% extra snaring power when both are at max rank.
The debuff triggered by Frostfire Bolt has both the snare and a DoT effect combined, so taking at least two ranks of this talent makes the DoT effect tick one more time.
Patch 3.2.0 (04-Aug-2009): In addition to its existing effects, this talent now also causes the mage's Chill effects to reduce healing received by the victim by 7/13/20%.